This invention relates to a bottom dump trailer and particularly to an arrangement for controlling the amount of movement of at least one door of a bottom dump trailer for adjustment of the opening at the door.
Bottom dump trailers are well known and widely used for transportation of gravel and other pourable solids. One example of a trailer of this type is shown in U.S. Pat. No. 5,131,722 of the present applicant issued Jul. 21, 1992 and the present invention is an improvement over the arrangement shown in that patent. The trailer generally comprises a frame having ground wheels on the frame for transportation of the frame across the ground. A hopper is mounted on the frame with converging side walls which extend inwardly and downwardly to an open bottom of the hopper through which the pourable material can be dumped. Across the bottom on the outside is provided a pair of clam shell type doors which pivot about respective axes which are parallel and arranged above the opening so that in a closed position the doors abut at a central line of contact below the open bottom. A hydraulic cylinder is generally provided together with a control linkage which operates to move the doors simultaneously outwardly from the closed position so that the doors pivot outwardly and upwardly around the bottom edge of the hopper to define an opening between the doors through which the material can be dumped.
It is necessary in a device of this type to be able to adjust the size of the opening. Generally the hydraulic cylinder and linkage is arranged so that it simply moves the doors from the closed position to a wide open position at which the doors are halted either by the end of the stroke of the hydraulic system or by an engagement of the door with some part of the frame. It is however necessary in many cases to control this opening to a reduced width so that the dumping of the material takes place in a controlled manner to form a windrow as the trailer is moved forward.